Bioequivalence of liquid and reconstituted lyophilized etanercept subcutaneous injections

The objective of this study was to compare the pharmacokinetics of liquid and reconstituted lyophilized etanercept. This single-center, open-label study had a 2-period crossover design in which 36 healthy subjects were randomly assigned in a 1:1 ratio to etanercept (liquid/lyo or lyo/liquid). The treatments were separated by 28 days. Blood samples were obtained predose and at 10 predetermined time points postdose. Serum concentrations were determined by enzyme-linked immunosorbent assay. Noncompartmental pharmacokinetic parameters were analyzed using a standard crossover analysis of variance model. Thirty-three subjects completed both treatment periods. Geometric mean values (adjusted) of area under the serum drug concentration-time curve from time zero to the time of the final quantifiable sample, area under the serum drug concentration-time curve from time zero to infinity, and maximum concentration obtained with the 50-mg/mL liquid etanercept injection were 93.0%, 90.7%, and 98.5% of the respective parameters for 2 injections of 25 mg/mL reconstituted formulation. All associated confidence intervals were within the predefined equivalence interval of 80% to 125%. No differences in safety profiles of the 2 formulations were apparent. Liquid etanercept was bioequivalent to the reconstituted lyophilized etanercept formulation.